Acrylic rubbers are rubber materials combining hot oil resistance, thermal aging resistance, and weather resistance, which are widely used as automotive rubber components such as packings, seals, valve stems, and oil deflectors for the transmission or crankshaft systems.
However, the inherent elasticity of the acrylic rubbers cause the resulting molded products to have a high friction coefficient or high tackiness on their surfaces. In applications requiring low-friction properties, it is required to improve the low-friction properties on the surface of the molded product.
In the above situation, Patent Literature 1, for example, discloses an acrylic rubber composition containing 0.5 to 6 parts by weight of an alkylene bis higher fatty acid amide, based on 100 parts by weight of acrylic rubber, to reduce friction and improve friction wear characteristics.
Patent Literature 2 discloses a resin composition containing (A) a fluoropolymer including vinylidene fluoride as a main repeating unit, (B) an acrylic rubber, (C) silica, and (D) carbon black, the resin composition having a ratio of the fluoropolymer (A) to the acrylic rubber (B) of 40/60 to 90/10 (w/w) and containing the silica (C) in an amount of 10 to 40 parts by weight and the carbon black (D) in an amount of 5 to 20 parts by weight, based on 100 parts by weight of the total of the fluoropolymer (A) and the acrylic rubber (B), in an effort to provide an inexpensive, low-density resin composition that satisfies required properties including oil resistance, abrasion resistance, heat resistance, and flexibility, has a favorable extrudability, and prevents production problems.
Patent Literature 3, which aims to provide a rubber composition thermally stable at high temperatures for a long period of time, discloses a cross-linkable rubber composition containing: (A) a rubber composite in which a fluororubber and an acrylic rubber are dispersed in each other, the fluororubber including polymerized units based on hexafluoropropylene and vinylidene fluoride and/or tetrafluororoethylene and the acrylic rubber including a cross-linkable hydroxy group or a crosslinkable chlorine atom in the molecule; (B) an acid acceptor including a metal oxide and/or a metal hydroxide; and (C) a vulcanization accelerator including a quaternary ammonium salt and/or a quaternary phosphonium salt. It also teaches that the composite (A) can be obtained by mixing and dispersing fluororubber latex and acrylic rubber latex in the latex state, followed by salting-out and coagulation.